run IEEE14-4th-order examples errors

[hzgzh]

how to fix it

ERROR: type FourthOrderEq has no field U
Stacktrace:

getproperty(::FourthOrderEq, ::Symbol) at .\Base.jl:33
initial_guess(::PowerGrid) at C:\Users\Administrator.julia\packages\PowerDynamics\Bze9U\src\operationpoint\operationpoint.jl:25
find_operationpoint(::PowerGrid, ::Nothing; p0::Nothing, t0::Float64, sol_method::Symbol, sol_kwargs::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}) at C:\Users\Administrator.julia\packages\PowerDynamics\Bze9U\src\operationpoint\operationpoint.jl:135
find_operationpoint at C:\Users\Administrator.julia\packages\PowerDynamics\Bze9U\src\operationpoint\operationpoint.jl:127
top-level scope at c:\code\PowerDynamicsExamples\ieee14-4th-order\runexample.jl:16
include_string(::Function, ::Module, ::String, ::String) at .\loading.jl:1088
ERROR: type FourthOrderEq has no field U
Stacktrace:

getproperty(::FourthOrderEq, ::Symbol) at .\Base.jl:33
initial_guess(::PowerGrid) at C:\Users\Administrator.julia\packages\PowerDynamics\Bze9U\src\operationpoint\operationpoint.jl:25
find_operationpoint(::PowerGrid, ::Nothing; p0::Nothing, t0::Float64, sol_method::Symbol, sol_kwargs::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}) at C:\Users\Administrator.julia\packages\PowerDynamics\Bze9U\src\operationpoint\operationpoint.jl:135
find_operationpoint at C:\Users\Administrator.julia\packages\PowerDynamics\Bze9U\src\operationpoint\operationpoint.jl:127
top-level scope at c:\code\PowerDynamicsExamples\ieee14-4th-order\runexample.jl:16
include_string(::Function, ::Module, ::String, ::String) at .\loading.jl:1088

[SabineAuer]

thank you for your hint. This is indeed a bug in PowerDynamics that sneaked into the latest release. This problems appears when the slack bus is not the first node. It will be fixed in the next minor release of PowerDynamics.